Quote:
Originally Posted by Ether
A cycle is one repeating pattern. It's a good way to define an encoder because it's independent of how you plan to use (decode) the signal.
The space between the red lines is one cycle.
One cycle can be 1 count (if you are counting only rising edges on one channel); or 2 counts (if you are counting only rising edges on 2 channels); or 4 counts (if you are counting rising and falling edges on 2 channels).
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At best that is a matter of 2 differring terms for the same thing.
Yes using cycle in that context seemingly eliminates the idea you can get 4 pulses from the decoder circuit, but it ignores that not all decoders are 4x decoders.
What is the difference between a cycle and a pulse in a 1x decoder? Nothing. Even over time, a bunch of pulses and a bunch of cycles, still nothing.
Granted: to the point of the OP, U.S. Digital's use of the term is what matters so I will accept the cycles per revolution in their case is 4x lower than the potential PPR as they use the terms. I prefer to think of them the other way and simply assume the quadrature decoder circuit is 1x unless provided as part of the encoder assembly.
Still a lot of good information in here on the point, minus the ambiguity of the terms. The ambiguity of the term is itself notable.
Quote:
Originally Posted by asid61
If your encoders fail a lot, you may want to consider just switching to magnetic encoders. 115 has killed many, many US Digital encoders in its time.
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Also: the failure rate for that style encoder Ether linked has to do with the end play of the shaft with the encoder disc. My MaxNC servos have eventually had encoder failures at the back of the steppers because the axis coupled to the shaft of the stepper exerts at times enough vibration (screw lash) and force to displace the disc and either scratch it or put it out of range of the detector. MaxNC has historically used a similar encoder from other companies and they suffered the same fate. I solved this problem using sealed encoders, a timing belt and a mount for the encoder. With 12 axis between these machines I'd have spent $1,400 on fixing those encoders or more by now without making those changes. Point being - I am noting a limitation of that style encoder not taking a shot at U.S. Digital.